A first seal is arranged on a shaft in a known filtration apparatus of this type through which the filtrate is drained. The seal extends over the full radial distance between this shaft and the oppositely arranged inner wall of the housing which encloses the shaft. Thus, the seal rotates when the hollow shaft rotates so that the seal rubs on the fixed container wall. Accordingly, after only a relatively short period of use, the seal becomes worn to such an extent that it has to be replaced by a new seal. However, this entails a substantial amount of assembly effort.
It is accordingly an object of the invention to provide a filtration apparatus which avoids wear of the first seal due to forces acting on the hollow shaft.